Tear shaping for refractive correction

ABSTRACT

A lens for refractive tear shaping, including a curved lens body defining an anterior partial thickness cavity indented into its anterior surface. The anterior partial thickness cavity has an anterior facing tear shaping surface structured to form a tear lens within the anterior partial thickness cavity. The anterior partial thickness cavity is structured to define a tear lens within the anterior partial thickness cavity by interaction between a tear film of the eye and the anterior facing base tear shaping surface. The posterior curvature of the tear lens is dependent on the shape of the anterior facing base tear shaping surface.

RELATED APPLICATION

This application is a continuation of application Ser. No. 15/947,136,filed Apr. 6, 2018, entitled “Tear Shaping for Refractive Correction,”now U.S. Pat. No. 10,678,067, which is hereby fully incorporated hereinby reference.

TECHNICAL FIELD

The invention generally relates to contact lenses and refractivecorrection by application of contact lenses or other structures to theeye.

BACKGROUND

Known contact lenses generally cover virtually the entire cornea orcover the cornea centrally while leaving a portion of the peripheralcornea uncovered. Contact lenses known to the Applicant achieverefractive correction because of the optical nature of an opticallytransparent, rigid, semi-rigid or flexible material that refracts lightand thus alters the refraction of light striking the cornea and passingthrough the other optical parts of the eye to an image formed on theretina.

The concept of a tear lens is known to exist in the context ofconventional contact lenses. The tear lens is formed by a layer of tearsbounded on an anterior surface by the back of a contact lens opticalzone and at a posterior surface of the tear lens by the surface of thecorneal epithelium. A tear lens, as understood in this conventionalsense, contributes to refractive correction primarily in the context ofrigid contact lenses. This is because the posterior surface of the rigidcontact lens maintains its shape and curvature independent of the shapeof the cornea and affects the focusing of light in addition to therefractive power of the contact lens. While a tear lens technicallyexists in the context of flexible or soft contact lenses, the effect ofthe tear lens on refraction is negligible because of the generalconformity of the soft contact lens shape to the shape of the cornea.

Numerous possible complications are known to exist with use of contactlenses on the cornea even though modern contact lenses cause fewercomplications than contact lenses of decades ago. The presence ofcontact lenses can lead to stasis and entrapment of the tear film whichcan lead to an accumulation of corneal epithelial waste products in theentrapped tear film. Corneal epithelial waste products in high enoughconcentrations can be toxic to the cells of the corneal epithelium.Mechanical interaction between the posterior surface of the contact lensand the corneal epithelium can lead to abrasion or distortion.Entrapment of solid objects, however tiny between the posterior surfaceof the contact lens and the anterior corneal epithelium can also lead tocorneal epithelial abrasion. Under some circumstances, the reduction ofoxygen available to the corneal epithelium by having the barrier of thecontact lens between the corneal epithelium and the atmosphere can leadto health complications for the corneal epithelium as well.

There is still room for improvement in the arts of refractive correctionby application of lenses and other structures to the eye.

SUMMARY

Embodiments of the invention solve many of the above stated problems byproviding a lens having an anterior central cavity which centers on theoptical axis of the eye or by other structures which can be applied tothe eye to create a desired refractive effect by tear shaping.

According to an example embodiment, the central opening is structuredsuch that capillary action forms a meniscus of tears in the opening.According to an example embodiment of the invention, the inventive lensis structured so that a concave meniscus is formed. The concave meniscusis provided for correction of myopia. It is expected that a concavemeniscus will form in a relatively larger diameter opening according toembodiments of the invention. According to an example embodiment of theinvention, the diameter of the central opening or central cavity fallsin a range from 1.0 to 5.0 millimeters. According to another exampleembodiment the diameter of the central opening falls in a range from 2.0to 3.0 millimeters and in another example embodiment 2.5 to 2.8millimeters. A further example embodiment presents a central opening of2.8 to 3.5 millimeters.

According to another example embodiment of the application, a convexmeniscus is formed. A convex meniscus is expected to form in a case of asmaller diameter opening in the lens which generally overlies theoptical axis of the eye.

Formation of the tear meniscus is affected by a number of factorsincluding: tear production, rate of evaporation; temperature, posture ofthe lens user. These factors can be considered in design of the lensaccording to the invention.

In the case of a central cavity, the anterior surface of the cavitylocated on the posterior surface of the lens borders and determines theshape of the tear film posterior to the lens and between the posteriorlens and the anterior cornea. The tears thus form a lens component thathas a refractive effect in addition to the refractive effect of thecontact lens.

According to another example embodiment of the invention, the opening isnon-circular in structure. For example, an oval opening is expected tocreate a meniscus having a first curvature in a first axis and a secondcurvature in a second axis and thereby permitting correction ofastigmatism by the tear meniscus formed. According to exampleembodiments of the invention, the central opening may be oval in shapeor polygonal having a first axis longer than a second axis to achievethe astigmatic correction.

According to example embodiments of the invention, the cross-sectionalshape of the edge or periphery of the opening may vary when viewed incross-section.

According to an example embodiment, the cross-sectional shape of theperiphery of the opening may demonstrate a thick rim. According toanother example embodiment, the cross-sectional shape of the peripheryof the opening may demonstrate the thin rim.

According to another embodiment, the cross-sectional shape of theperiphery of the opening may demonstrate a straight rim. The straightrim may be substantially radial in orientation as compared to thecurvature of the lens and opening or may be tilted to create an acute orobtuse angle relative to a tangent to the corneal surface.

According to another example embodiment of the invention, the peripheryof the opening may demonstrate a concave shape when viewed in crosssection.

According to another example embodiment of the invention, the peripheryof the opening may demonstrate a convex shape when viewed in crosssection.

According to another example embodiment of the invention, thecross-sectional shape of the periphery of the opening may demonstrate apolygonal cross-section which may be either concave or convex.

According to other example embodiments of the invention, thecross-sectional shape of the rim may vary around the circumference ofthe periphery of the opening. For example, a portion or portions of theperiphery of the opening when viewed in cross-section may be concavewhile other portions may be convex.

According to another example embodiment of the invention, the perimeterof the rim may vary in shape when viewed in an anterior-posteriordirection.

According to another example embodiment of the invention, the perimeterof the rim viewed anterior to posterior may have a smooth continuouscurved shape.

According to another example embodiment of the invention, the perimeterof the rim when viewed anterior to posterior may include indentations inthe rim perimeter.

According to another example embodiment of the invention, the rimperimeter may include appendages extending inwardly from the rim.

According to another example embodiment of the invention, the peripheryof the opening when viewed in an anterior to posterior direction mayhave a circular shape. According to another example embodiment of theinvention, the periphery of the opening when viewed in an anterior toposterior direction may have an oval shape and according to anotherexample embodiment of the invention, the periphery of the opening inviewed in an anterior to posterior direction may have a polygonal shape.The polygonal shape may include a regular polygon or an irregularpolygon shape. The polygon may be generally radially symmetrical or maybe other than radially symmetrical.

According to another example embodiment of the invention, a contact lensincludes a centrally located partial depth opening or cavity locatedcentrally on the posterior concave surface of the lens. For example, thecavity may have a diameter of 2 mm to 5 mm at the center of theposterior surface of the lens. According to an example embodiment of theinvention, the center or the centroid of the partial depth cavity iscollinear with the optical center of the lens and when placed on an eyeis substantially aligned with the optical axis of the eye. The partialdepth cavity is bounded by an anterior surface which coincides with theposterior surface of the lens within the cavity. In situ, the cavity isalso bounded by the anterior surface of the cornea. The anterior toposterior depth of the cavity according to an example embodiment is notless than 25 microns and not more than 100 microns as measured from acenter of the tear shaping surface and to an imaginary extension of abase curve of the curved lens body. In this embodiment the base curve ofthe lens is considered to be the posterior curve immediately surroundingthe partial depth cavity.

According to example embodiments of the invention, the shaped posteriorsurface of the lens within the cavity may have a radius of curvaturethat is more or less than the radius of curvature of the anterior corneain the region of the cornea where the cavity is located when the lens ison an eye. According to known optics, a shaped posterior surface of thelens having a radius of curvature greater than the radius of curvatureof the anterior corneal surface will generally provide a space in whicha negative powered tear lens is formed. Conversely, a shaped posteriorsurface lens bounding the cavity having a radius of curvature less thanthe radius of curvature of the corneal region that bounds the rear ofthe cavity will generally lead to a tear lens having positive opticalpower.

According to another example embodiment of the invention, the lens bodymay define one or more passages having a diameter of no more than about2 microns and no less than about 0.5 microns. These passages extend fromthe posterior lens to the anterior lens surface through the body of thecontact lens. The openings are expected to promote tear exchange andoxygen exchange between tears under the lens and tears anterior to thelens.

According to another example embodiment of the invention, the lens orstructure for refractive tear shaping includes a lens body presenting ananterior partial thickness cavity. A contact lens, for example, a softcontact lens, having a partial thickness cavity can be placed on an eye.In situ, the partial thickness cavity will fill with tear fluid. Thecolumn of tear fluid, in combination with the surface curvature of thebase or posterior surface of the cavity, the layer of contact lensmaterial behind the partial thickness cavity, the tear film and corneamake up a complex optic or optical combination that provides severalelements of adjustable dimensions and properties that may be utilized toform an optic or optical combination having desired refractiveproperties. For example, the shape and contour of the base of thepartial thickness cavity may be varied in curvature, toricity, perimetershape or a combination of the foregoing. In a further example, thethickness of the material way are posterior to the base of the partialthickness cavity may be varied. In another example, the base orposterior curve of the contact lens may be altered in curvature ortoricity. The base of the partial thickness cavity, the base curve ofthe contact lens or both may include a diffractive optical surface.

For example, the base surface or posterior base of the partial thicknesscavity may have a curvature greater than, less than or equal to thecurvature of the posterior surface of the contact lens which generallyconforms to the anterior surface of the cornea.

According to another example embodiment, the base surface or posteriorbase of the partial thickness cavity may have a diffractive surfacerelief.

According to an example embodiment of the invention, a soft or rigidcontact lens has a partial depth cavity located proximate a center ofthe lens to form and accommodate a tear fluid reservoir.

A diameter of the partial depth cavity, according to an exampleembodiment of the invention, is in the range of 2.0 mm to 6.0 mm.According to another example embodiment the diameter is between 3.0 mmand 5.0 mm.

The contact lens, according to an example embodiment, has a thicknessranging from 50 μm to 500 μm, according to another example embodimentbetween 80 μm and 350 μm at its optical center. The partial thicknesscavity is bounded posteriorly by a layer of contact lens material thethickness of which may vary between 10 μm and 100 μm according to anexample embodiment. According to another example embodiment thethickness may vary between 25 μm and 75 μm.

The thickness of a contact lens is generally measured as a centerthickness. That is, the thickness of the contact lens at the geometricalcenter of the contact lens. In the case of embodiments of the presentinvention, the center thickness is affected by the presence of theanterior partial thickness cavity. Accordingly, center thickness in thecontext of this embodiment of the invention is considered to be thethickness from the posterior concave surface of the contact lens to animaginary extension of the anterior surface of the contact lens thatwould exist if the partial thickness cavity were not present.

According to example embodiments of the invention, when the contact lensis centered on the cornea the partial thickness cavity is centered sothat its center generally aligns with the corneal apex. It is expectedthat typically the error in centration of the partial depth cavity withrespect to the corneal apex is less than approximately 0.5 mm and inanother example embodiment less than 0.25 mm. The corneal apex generallycoincides with the visual axis of the eye although there is somevariation between the location of the visual axis and the corneal apex.

According to an example embodiment of the invention, the base surface ofthe partial depth cavity has a radius of curvature less than the radiusof curvature of the posterior surface of the contact lens. According tothis example embodiment of the invention, the optic or opticalcombination created by the partial depth cavity extending over thecenter of the contact lens optics includes three surfaces. The threesurface include the first interface between the tears that fill theanterior partial depth cavity, the second interface between the tearsfilling the cavity and the material of the lens at the base of thepartial depth cavity and the third interface between the posteriorconcave surface of the lens and the tear film layer behind it. Inaddition, the anterior corneal surface optically interacts with thisexample embodiment and thus, a fourth surface is taken into account. Thefourth surface is formed by the anterior cornea which has a radius ofcurvature r₁. The third surface is formed by the posterior surface ofthe contact lens for example, a soft contact lens, which has a radiusr₂. The base surface of the partial depth cavity which forms the secondsurface has a radius of curvature r₃. The anterior surface of thecontact lens to which the interface between the tear film and theatmosphere is expected to conform, has a radius of curvature r₄.

To summarize according to an example embodiment:

r₁ represents the radius of curvature of the anterior corneal surface;

r₂ represents the radius of curvature of the posterior surface of thesoft contact lens;

r₃ represents the radius of curvature of the base surface of the partialdepth cavity; and

r₄ represents the radius of curvature of the anterior surface of thecontact lens or anterior interface of the tear film within the partialthickness cavity.

If it is determined that the anterior tear film does not substantiallyconform to the anterior curvature of the contact lens adjustments can bemade to the calculation to take this factor into account as isunderstood by those having skill in the art.

In a typical circumstance utilizing a soft contact lens, r₁ is equal tor₂ or approximately equal to r₂ unless a keratoprosthesis (an artificialcorneal implant) is present in the cornea. The contact lens may have atotal power that is positive or negative or the contact lens may have nonet refractive power. Radius of curvature r₄ can be less than, more thanor equal to r₂. The relationship between r₃ and r₂ along with thethickness of the optical segment determine the refractive power of theoptical segment that is represented by the central zone of the partialdepth cavity when filled with tears. Toric optical surfaces andconsequent astigmatic focusing can also be taken into account utilizingknown optical principles. An optical train of this sort can be modeledusing various optical software programs, for example, Zemax.

In this example embodiment, the central optical element created by thepartial depth cavity is expected to be used to correct hyperopia,provide add power to fully meet or partially meet accommodative needs ofa patient with presbyopia or be used to meet other refractiverequirements related to for example, astigmatism.

According to another example embodiment, the base surface of the partialdepth cavity has a radius of curvature more than the radius of curvatureof the posterior surface of the contact lens. Accordingly, it isexpected that the central optical element will provide a negativerefractive power that may be used to provide an enhancement of the fieldof view and depth of field, as an example.

According to another example embodiment, the base surface of the partialthickness cavity includes a diffractive surface profile. The diffractivesurface profile may for example include a phase plate surface for phasemodulation or, according to another example embodiment, a phase wrappedsurface for amplitude modulation.

Typically, the diffractive optic according to example embodiments of theinvention is designed according to equation 1.r _(n)=2nfλ  Eq (1)wherein r represents the radius of curvature of the diffractive element,n represents refractive index or the refractive index difference (if thediffractive optic is immersed in a fluid having a refractive index otherthan that of air), f represents focal length and λ is the wavelength oflight. According to example embodiments of the invention, thediffractive optical element is immersed in a fluid, the tear film,having a refractive index different than air which is known.

According to example embodiments of the invention, a diffractive opticmay be used to provide a plus power for augmentation of naturalaccommodation for viewing near objects such as reading. Expectedadvantages are that a diffractive optic may demonstrate a wider field ofview and also may be utilized to correct for spherical aberration orastigmatism.

The above summary is not intended to describe each illustratedembodiment or every implementation of the subject matter hereof. Thefigures and the detailed description that follow more particularlyexemplify various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

Subject matter hereof may be more completely understood in considerationof the following detailed description of various embodiments inconnection with the accompanying figures, in which:

FIG. 1 is an anterior to posterior view of a lens for refractive tearshaping having a circular central opening therein;

FIG. 2 is an anterior to posterior view of a lens for refractive tearshaping having an oval central opening therein;

FIG. 3 is a lens for refractive tear shaping having a polygonal openingtherein;

FIG. 4 is an anterior to posterior view of a lens for refractive tearshaping having a stellate opening with indentations according to anexample embodiment of the invention;

FIG. 5 is an anterior to posterior view of a lens for refractive tearshaping having a stellate opening with appendages according to anexample embodiment of the invention;

FIG. 6 is an anterior to posterior view of a lens for refractive tearshaping having a generally rectangular polygonal opening thereinaccording to an example embodiment of the invention;

FIG. 7 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea and with a concave tear meniscus according to anyexample embodiment of the invention;

FIG. 8 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea with a convex tear meniscus according to an exampleembodiment of the invention;

FIG. 9 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea with a central opening having inward angled edgesand a concave tear meniscus according to an example embodiment of theinvention;

FIG. 10 is a cross-sectional view of a lens for refractive tear shapingin situ on a cornea with a concave tear meniscus and outwardly anglededges according to an example embodiment of the invention;

FIG. 11 is a cross-sectional view of a lens for refractive tear shapinghaving an opening with concave peripheral edges according to an exampleembodiment of the invention with the tear meniscus not depicted;

FIG. 12 is a cross-sectional view of a lens for refractive tear shapinghaving an opening with convex peripheral edges in situ on a corneaaccording to an example embodiment of the invention with the tearmeniscus not depicted;

FIG. 13 is a lens for refractive tear shaping in situ on a cornea withan opening having polygonal peripheral edges with the tear meniscus notdepicted;

FIG. 14 is a cross-sectional view of a contact lens having a partialdepth cavity with an anterior boundary flatter in curvature than thecornea in situ on a cornea according to an example embodiment of theinvention;

FIG. 15 is a cross-sectional view of a partial depth cavity contact lenshaving a curvature steeper than the anterior cornea;

FIG. 16 is a cross-sectional view of a contact lens having a partialdepth cavity flatter in curvature than the cornea, the lens body beingpierced by a series of holes;

FIG. 17 is a cross-sectional view of a contact lens with a partial depthcavity having a steeper curvature than the cornea, the lens body piercedby a series of holes;

FIG. 18 is a cross-sectional view of a contact lens according to anotherexample embodiment of the invention in situ on an eye;

FIG. 19 is a cross-sectional view of a contact lens according to anotherexample embodiment of the invention in situ on the eye; and

FIG. 20 is a cross-sectional view of another contact lens according toan embodiment of the invention in situ on an eye;

FIG. 21 depicts a contact lens with a partial thickness cavity at thecenter in an anterior convex surface according to an example embodimentof the invention

FIG. 22A depict a section of a partial thickness cavity with a basesurface of the partial thickness cavity having a curvature greater thana posterior surface of the contact lens according to an exampleembodiment of the invention;

FIG. 22B depicts a section of a partial thickness cavity with a basesurface of the partial thickness cavity having a curvature less than aposterior surface of the contact lens according to an example embodimentof the invention;

FIG. 22C depicts a section of a partial thickness cavity with a basesurface of the partial thickness cavity having a diffractive surfacerelief according to an example embodiment of the invention

FIG. 23A depicts an example diffractive optical element as a surfaceprofile at the base of a partial thickness cavity in a soft contact lensaccording to an example embodiment of the invention;

FIG. 23B depicts an example diffractive optical element is a surfaceprofile at the base of a partial thickness cavity in a soft contact lensaccording to an example embodiment of the invention;

FIG. 24 depicts an optical train according to an example embodiment ofthe invention that may be modeled using a typical optical softwareprogram, for example, Zemax.

While various embodiments are amenable to various modifications andalternative forms, specifics thereof have been shown by way of examplein the drawings and will be described in detail. It should beunderstood, however, that the intention is not to limit the claimedinventions to the particular embodiments described. On the contrary, theintention is to cover all modifications, equivalents, and alternativesfalling within the spirit and scope of the subject matter as defined bythe claims.

DETAILED DESCRIPTION

Referring to FIGS. 1-13 , embodiments of the invention are directed tolens or structure for refractive tear shaping 20 wherein refractivecorrection is achieved or enhanced by the shaping of the tear film.

Referring particularly to FIGS. 1-6 , lens for refractive tear shaping20 according to an example embodiment of the invention generallyincludes lens body 22 having peripheral edge 24 and defining centralopening 26. Central opening 26 is surrounded by a tear shaping edge 28.According to the depicted embodiment, tear shaping edge 28 definescircular central opening 30. Tear shaping edge 28 can have a number ofcross sectional structures and shapes as described below.

Referring now to FIG. 2 , another embodiment of lens for refractive tearshaping 20 is depicted. The depicted embodiment includes lens body 22having peripheral edge 24 and elliptical or oval central opening 32.Elliptical or oval central opening 32 is bounded by tear shaping edge28.

Referring to FIG. 3 , another embodiment of lens for refractive tearshaping 20 is depicted having polygonal central opening 34. Polygonalcentral opening 34 is depicted as an irregular hexagon, howeverpolygonal central opening 34 may have more or less than six sides andsix vertices.

Referring particularly to FIGS. 2 and 3 , elliptical or oval centralopening 32 and polygonal central opening 34 may have long axis 36 andshort axis 38.

Referring now to FIG. 4 , according to another embodiment, lens forrefractive tear shaping 20 defines stellate opening 40 havingindentations into the material of the lens surrounding stellate opening40. While stellate opening 40 is depicted as circularly symmetrical,stellate opening 40 may also have long axis 36 and short axis 38.

Referring now to FIG. 5 , another embodiment of lens for refractive tearshaping 20 is depicted. According to the depicted embodiment, stellateopening with appendages 44 is depicted. Appendages 46 extend inwardlyfrom outer edge 48. While depicted as circularly symmetrical, stellateopening with appendages 44 may also have long axis 36 and short axis 38.

Referring now to FIG. 6 , lens for refractive tear shaping 20 withrectangular opening 50 is depicted. Rectangular opening 50 is depictedhaving a particular proportional aspect ratio, however this should notbe considered limiting as the aspect ratio of rectangular opening 50 maybe altered by altering the length of long axis 36 as compared to shortaxis 38.

Referring now to FIGS. 7-13 , cross-sectional views of exampleembodiments of lens for refractive tear shaping 20 are depicted.

Referring particularly to FIG. 7 , an embodiment of the inventionincluding parallel tear shaping edge 52 is depicted. It is noted thatlens body 22 in the embodiment depicted in FIG. 7 that parallel tearshaping edge 52 is generally parallel on opposing sides of centralopening 26. Also depicted in FIG. 7 is concave tear meniscus 54. Concavetear meniscus 54 affects a negative refractive power due to its concaveshape and is expected to contribute focusing power for correction ofmyopia. It is expected that the concavity of concave tear meniscus 54will vary with the size of central opening 26 and with the depth 56 oftear shaping edge 28.

It is expected that to a certain point smaller diameter of centralopening 26 will create a more steeply curved concave tear meniscusimparting greater negative refractive power and stronger correction formyopia. It is also expected that increasing depth 56 of tear shapingedge 28 will increase negative refractive power to a certain degree. Asdiscussed above, central opening 26 may have various shapes, some ofwhich include a long axis 36 and short axis 38.

It is expected that by judicious selection of the size of long axis 36and short axis 38 that astigmatism may be corrected by creating aconcave tear meniscus 54 having different shape and therefore differingpower on various meridians.

Referring now to FIG. 8 , lens for refractive tear shaping 20 havingparallel tear shaping edge 52 is sized and configured to create convextear meniscus 58. It is expected that when the size of central opening26 is reduced to a sufficient degree, convex tear meniscus 58 will beformed in central opening 26. FIG. 8 depicts parallel tear shaping edge52 along with a smaller diameter central opening 26 than does FIG. 7 .It is expected that when the size of central opening 26 and depth 56 oftear shaping edge are appropriate convex tear meniscus 58 will beformed.

Referring now to FIG. 9 , lens for refractive tear shaping 20 withanterior acute tear shaping edge 60 is depicted. It is noted thatanterior acute tear shaping edge 60 is arranged so that tear shapingedge 28 narrows from posteriorly-to-anteriorly. Concave tear meniscus 54is also depicted. It is expected that anterior acute tear shaping edge60 will create a more concave tear meniscus 54 thus, creating greaternegative refractive power to concave tear meniscus 54.

Referring now to FIG. 10 , lens for refractive tear shaping 20 havinganterior obtuse tear shaping edge 62 is depicted. Anterior obtuse tearshaping edge 62 is structured so that central opening 26 is wideranteriorly and narrower posteriorly. It is expected that anterior obtusetear shaping edge 62 will create a flatter concave tear meniscus 54 asdepicted in FIG. 10 thus, creating a concave tear meniscus having lessnegative refractive power than parallel tear shaping edge 52 having asimilar posterior diameter.

Referring now to FIG. 11 , lens for refractive tear shaping 20 havingconcave tear shaping edge 64 is depicted. In FIG. 11 , no tear meniscus66 is depicted for clarity. Concave tear shaping edge 64 includesanterior edge 68, posterior edge 70 and concave portion 72.

Referring now to FIG. 12 , lens for refractive tear shaping 20 withconvex tear shaping edge 74 is depicted. No tear meniscus 66 is depictedfor clarity. In the depicted embodiment, convex tear shaping edge 74 hasa radius of curvature approximately equal to half of depth 56 of tearshaping edge 20. This should not be considered limiting however as theradius of curvature of convex tear shaping edge 74 may vary.

Referring now to FIG. 13 , lens for refractive tear shaping 20 withfaceted tear shaping edge 76 is depicted. Faceted tear shaping edge 76presents anterior edge 78, posterior edge 80 and internal angle portion82.

Lens for refractive tear shaping 20 according to the various embodimentsdescribed herein may be formed from hydrogel polymers of the types usedin soft contact lens that are now available or any hydrogel polymermaterials to be developed in the future. Hydrogel polymers are generallywater absorbent and hydrogel polymers may be used to manufacture lensesfor refractive tear shaping 20 according to the invention by methodsincluding but not limited to lathe cutting, cast molding, spin castingand injection molding. Lenses for refractive tear shaping 20 may also bemanufactured from rigid oxygen permeable materials by knownmanufacturing processes including lathe cutting. It is to be understoodthat lens for refractive tear shaping 20 may be manufactured by anyknown contact lens manufacturing process or contact lens manufacturingprocesses to be developed in the future.

Lenses for refractive tear shaping 20 are expected to be made indiameters ranging from approximately 5 mm to 16 mm. Certain features oflens for refractive tear shaping 20 such as the diameter of centralopening 26, the structure of tear shaping edge 28, the appropriatelength of long axis 36 and short axis 38 to achieve desired refractivecorrection are expected to be developed with a certain degree ofexperimentation. It is expected that this degree of experimentation willnot be undue and that those of ordinary skill in the art based on thepresent application disclosure will be able to engage in suchexperimentation without significant difficulty.

It is expected that for formation of concave tear meniscus 54, thatsmaller diameter central openings 26 will result in higher refractivepower of concave tear meniscus 54, thus permitting higher degrees ofrefractive correction for myopia. It is also expected that when thediameter of central opening 26 becomes sufficiently small, tear meniscus66 will transition from concave tear meniscus 54 to convex tear meniscus58. Determination of this transition diameter for transition is expectedto be achievable by reasonable levels of experimentation.

The effect of depth 56 of tear shaping edge 28 on refractive power oftear meniscus 66 also should be determinable by reasonableexperimentation. It is expected that greater depth 56 will generallycreate a thicker periphery of tear meniscus 66 resulting in higherdegrees to concavity of concave tear meniscus 54 and greater myopiccorrection.

Further, understanding of the effect of other features of the disclosedlenses including anterior acute tear shaping edge 60, anterior obtusetear shaping edge 62, concave tear shaping edge 64, convex tear shapingedge 74 and faceted tear shaping edge 76 are expected to be achieved byreasonable experimentation well within the ability of one of ordinaryskill in the art. It is expected that such experimentation will not beundue. It is also expected that the effect of stellate opening 40 withindentations 42 as well as stellate opening with appendages 44 andappendages 46 can also be determined experimentally.

Referring now to FIGS. 15-20 , according to another embodiment of theinvention, lens with partial depth cavity 84 is depicted in variousembodiments.

Referring to FIG. 14 , in the depicted embodiment, lens with partialdepth cavity 84 generally includes lens body 86 presenting peripheraledge 88, central partial depth cavity 90, tear shaping surface 92, andcavity peripheral edge 94. Lens with partial depth cavity 84 is depictedas resting adjacent corneal surface 96. FIG. 14 depicts lens withpartial depth cavity 84 having tear shaping surface 92 that is flatterin curvature than corneal surface 96, thus having a longer radius ofcurvature than corneal surface 96. Accordingly, in the depictedembodiment, tears underlying lens with partial depth cavity 84 generallyprovide a negative refractive power in addition to that provided by lenswith partial depth cavity 84 alone due to tear lens 98.

Another example embodiment of lens with partial depth cavity 84 isdepicted in FIG. 15 . Structures labeled in FIG. 15 are similar to thoselabeled in FIG. 14 but tear shaping surface 92 of lens with partialdepth cavity 84 depicted in FIG. 15 is curved more steeply than cornealsurface 96 thus having a radius of curvature less than corneal surface96 resulting in a positive powered tear lens 98.

Referring now to FIGS. 16 and 17 , according to the depicted embodiment,lens with partial depth cavity 84 includes at least one hole or passage100 through lens body 86 as depicted. In the depicted embodiments, lenswith partial depth cavity 84 presents central passage 102, firstperipheral passage 104 and second peripheral passage 106. Any number ofcentral passages 102 and peripheral passages 104 and 106 can be definedby lens body 86.

Referring to FIG. 18 , another embodiment of lens with partial depthcavity 84 is depicted. In the depicted embodiment, tear shaping surface92 presents small diameter, concave tear shaping surface 108. In thedepicted embodiment, cavity peripheral edge 94 includes generallyparallel sides 110. For the purposes of this application, generallyparallel sides 110 are considered to be generally parallel when they arewithin five degrees of parallel with each other.

Referring now to FIG. 19 , another embodiment of lens with partial depthcavity 84 is depicted. In the depicted embodiment, central, partialdepth cavity 94 is bounded by tear shaping surface 92 presenting concaveto plano tear shaping surface 112. In the depicted embodiment, concaveto plano tear shaping surface 112 is flatter in curvature and thus has alonger radius of curvature than corneal surface 96. In the depictedembodiment, cavity peripheral edge 94 presents non-parallel sides 114.Non-parallel sides 114 are considered to be non-parallel when the anglebetween non-parallel sides 114 is greater than five degrees relative toeach other. In the depicted embodiment, central, partial depth cavity 94has a cavity diameter 116 less than that of the pupil 118.

Referring now to FIG. 20 , in the depicted embodiment, central, partialdepth cavity 90 presents convex tear shaping surface 120 andnon-parallel sides 114. Convex tear shaping surface 120 is not onlyflatter than corneal surface 96 but it is shaped so that an anteriorsurface of tear lens 98 is by concave, thus providing a strongernegative power to tear lens 98.

According to another example embodiment, lens 86 further presents basecurve 122. Contrary to prior art base curve 121 is not the most centralcurve of lens body 86. The most central curve here is that of tearshaping surface 92. According to an example embodiment, base curve 122is the curve of the posterior lens that immediately surrounds centralpartial depth cavity 90. Depth 124 of central partial depth cavity 90 ismeasured from an imaginary extension of based curve 122 across centralpartial depth cavity 90 to a center of tear shaping surface 92.

Referring to FIG. 21 , according to another example embodiment theinvention, lens for refractive tear shaping 20 includes lens body 124presenting anterior partial thickness cavity 126. According to thedepicted example embodiment, soft contact lens 128 has overall diameter130 of 14.0 mm. Central thickness 132 of soft contact lens 128 isapproximately 0.50 mm. Note that central thickness 132 indicates whatthe central thickness of soft contact lens 128 would be absent thepresence of partial thickness cavity 126. These dimensions are presentedas an example only and are not to be considered limiting.

According to the depicted example embodiment:

r₁ represents anterior corneal radius of curvature of the anteriorcorneal surface;

r₂ represents posterior contact lens radius of curvature of theposterior surface of the soft contact lens;

r₃ represents partial depth cavity radius of curvature of the basesurface of the partial depth cavity; and

r₄ represents anterior contact lens radius of curvature of the anteriorsurface of the contact lens.

According to the depicted embodiment, posterior contact lens radius r₂is approximately 8.00 mm and anterior contact lens radius r₄ is alsoapproximately 8.00 mm. Partial depth cavity diameter 134 isapproximately is approximately 5.00 mm. Partial depth cavity depth 136is not specifically identified in this example but is less than centralthickness 132 of 0.50 mm.

Soft contact lens 128 as discussed herein according to an exampleembodiment, presents anterior partial thickness cavity 126. Partialdepth cavity diameter 34, according to example embodiments of theinvention, is in a range between 2.0 mm and 6.0 mm, and according toanother example embodiment is in a range of 3.0 mm to 5.0 mm.

Central thickness 132 is in a range of 50 μm to 500 μm according to anexample embodiment. According to another example embodiment, centralthickness 132 is in a range of 80 μm to 350 μm. Central thickness 132indicates what the central thickness 132 of soft contact lens 128 wouldbe absent the presence of partial thickness cavity 126.

Referring now to FIGS. 22A, 22B and 22C, for the purposes of thesedepictions it is assumed that the anterior corneal surface 138 andposterior contact lens surface 140 are coincident. In fact, a layer oftear film laser lies between the anterior corneal surface 138 andposterior contact lens surface 140 and can be taken into account byknown optical methods. Base surface 142 of anterior partial thicknesscavity 126 is also depicted.

According to FIG. 22A, base surface 142 has curvature 144 greater thanposterior contact lens service 140. It is of note that curvature andradius of curvature are reciprocal quantities.

According to FIG. 22B, base surface 142 has curvature 144 less thanposterior contact lens surface 140.

According to FIG. 22C, base surface 142 presents diffractive surfacerelief 144.

The diffractive surface relief 144 may, for example, include a phaseplate surface for phase modulation or according to another exampleembodiment a phase wrapped surface for amplitude modulation.

Typically the diffractive optic according to example embodiments of theinvention is designed according to equation 1.r _(n)=2nfλ  Eq (1)wherein r_(n) represents the radius of curvature of the diffractiveelement, n represents refractive index or the refractive indexdifference, if the diffractive optic is immersed in a fluid having arefractive index other than air, f represents focal length and λ is thewavelength of light. According to example embodiments of the invention,the diffractive optical element is immersed in a fluid, the tear film,having a known refractive index different than air.

Referring to FIG. 23A, an example diffractive surface relief 144 isdepicted. In the depicted embodiment, diffractive surface relief 144includes Fresnel surface 146 and plano surface 148. Wavelength of lightλ is also depicted along with optical wavefronts 150.

Referring to FIG. 23B, soft contact lens 128 is depicted with anteriorpartial thickness cavity 126 wherein base surface 142 includesdiffractive surface relief 144.

Base thickness 152 extending from base surface 142 to posterior contactlens surface 140 may vary in a range between, for example, 10 μm and 100μm. According to an example embodiment, base thickness 152 may be in therange of 25 μm to 75 μm.

Referring to FIG. 24 , optical train 154 is depicted. Optical train 154includes radii of curvature r₁ representing the corneal curvature, r₂representing the curvature posterior contact lens surface 140 of tearshaping lens 20, r₃ representing the radius of curvature of base surface142 of anterior partial thickness cavity 126 and r₄ representinganterior radius of curvature of tear fluid reservoir 156. Here, n₁represents diffractive index of the tear film between lens body 124 andthe cornea, n₂ represents refractive index of the contact lens materialand the n₃ represents the refractive index of the tear fluid reservoir156. Optical train 154 can be modeled using an optical software programsuch as, for example, Zemax.

In operation, lens for refractive tear shaping 20 is placed on an eyeoverlying the cornea of the eye. Lens for refractive tear shaping 20will typically center on the eye such that central opening 26, centralpartial depth cavity 94 or anterior partial thickness cavity 126 isapproximately centered on the cornea and is approximately aligned withthe visual axis of the eye. Tear lens 98 forms within central opening26, central partial depth cavity 94 or anterior partial thickness cavity126 as described above to provide desired refractive correction.

The present invention may be embodied in other specific forms withoutdeparting from the spirit of the essential attributes thereof;therefore, the illustrated embodiments should be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than to the foregoing description to indicatethe scope of the invention.

Various embodiments of systems, devices, and methods have been describedherein. These embodiments are given only by way of example and are notintended to limit the scope of the claimed inventions. It should beappreciated, moreover, that the various features of the embodiments thathave been described may be combined in various ways to produce numerousadditional embodiments. Moreover, while various materials, dimensions,shapes, configurations and locations, etc. have been described for usewith disclosed embodiments, others besides those disclosed may beutilized without exceeding the scope of the claimed inventions.

Persons of ordinary skill in the relevant arts will recognize that thesubject matter hereof may comprise fewer features than illustrated inany individual embodiment described above. The embodiments describedherein are not meant to be an exhaustive presentation of the ways inwhich the various features of the subject matter hereof may be combined.Accordingly, the embodiments are not mutually exclusive combinations offeatures; rather, the various embodiments can comprise a combination ofdifferent individual features selected from different individualembodiments, as understood by persons of ordinary skill in the art.Moreover, elements described with respect to one embodiment can beimplemented in other embodiments even when not described in suchembodiments unless otherwise noted.

Although a dependent claim may refer in the claims to a specificcombination with one or more other claims, other embodiments can alsoinclude a combination of the dependent claim with the subject matter ofeach other dependent claim or a combination of one or more features withother dependent or independent claims. Such combinations are proposedherein unless it is stated that a specific combination is not intended.

Any incorporation by reference of documents above is limited such thatno subject matter is incorporated that is contrary to the explicitdisclosure herein. Any incorporation by reference of documents above isfurther limited such that no claims included in the documents areincorporated by reference herein. Any incorporation by reference ofdocuments above is yet further limited such that any definitionsprovided in the documents are not incorporated by reference hereinunless expressly included herein.

For purposes of interpreting the claims, it is expressly intended thatthe provisions of 35 U.S.C. § 112(f) are not to be invoked unless thespecific terms “means for” or “step for” are recited in a claim.

The invention claimed is:
 1. A method of making a lens for refractivetear shaping, the method comprising: determining a refractive correctionfor the lens; determining a size and a shape of an anterior partialthickness cavity to be formed in the lens, based on the determinedrefractive correction; forming a curved lens body from an opticallytransparent material, the curved lens body having a peripheral edge,wherein a thickness of the lens body from the base surface to aposterior surface of the lens body is in a range of 10 μm to 100 μm;forming the anterior partial thickness cavity in an anterior surface ofthe lens body, wherein the anterior partial thickness cavity comprises:an anterior facing base surface; and an edge, wherein the anteriorfacing base surface and the edge are sized and shaped to form a tearlens within the anterior partial thickness cavity to provide thedetermined refractive correction.
 2. The method of claim 1, whereinforming the anterior partial thickness cavity comprises forming the basesurface to have a curvature greater than that of a posterior surface ofthe lens body.
 3. The method of claim 1, wherein forming the anteriorpartial thickness cavity comprises forming the base surface to have acurvature less than that of a posterior surface of the lens body.
 4. Themethod of claim 1, wherein forming the anterior partial thickness cavitycomprises forming the base surface to have a diffractive surface.
 5. Themethod of claim 4, wherein the diffractive surface is defined byrn=2nfλ wherein rn represents a radius of curvature of the diffractivesurface, n represents a refractive index or a refractive indexdifference, if the diffractive surface is immersed in a fluid having arefractive index other than air, f represents a focal length and λ is awavelength of light.
 6. The method of claim 4, wherein forming theanterior partial thickness cavity comprises forming the base surface tohave a shape selected from the group consisting of a convex and concave.7. The method of claim 1, wherein forming the anterior partial thicknesscavity comprises positioning the anterior partial thickness cavity at anoptical center of the lens body.
 8. A method of making a lens forrefractive tear shaping, the method comprising: determining a refractivecorrection for the lens; determining a size and a shape of an anteriorpartial thickness cavity to be formed in the lens, based on thedetermined refractive correction; forming a curved lens body from anoptically transparent material, the curved lens body having a peripheraledge; forming the anterior partial thickness cavity in an anteriorsurface of the lens body, wherein the anterior partial thickness cavitycomprises: an anterior facing base surface; and an edge, wherein theanterior facing base surface and the edge are sized and shaped to form atear lens within the anterior partial thickness cavity to provide thedetermined refractive correction, and wherein forming the anteriorpartial thickness cavity comprises forming the base surface to have adiffractive surface.
 9. The method of claim 8, wherein forming theanterior partial thickness cavity further comprises forming the basesurface to have a curvature greater than that of a posterior surface ofthe lens body.
 10. The method of claim 8, wherein forming the anteriorpartial thickness cavity further comprises forming the base surface tohave a curvature less than that of a posterior surface of the lens body.11. The method of claim 8, wherein forming the anterior partialthickness cavity further comprises positioning the anterior partialthickness cavity at an optical center of the lens body.
 12. The methodof claim 8, wherein a thickness of the lens body from the base surfaceto a posterior surface of the lens body is in a range of 10 μm to 100μm.
 13. The method of claim 8, wherein the diffractive surface isdefined byrn=2nfλ wherein rn represents a radius of curvature of the diffractivesurface, n represents a refractive index or a refractive indexdifference, if the diffractive surface is immersed in a fluid having arefractive index other than air, f represents a focal length and λ is awavelength of light.
 14. The method of claim 8, wherein forming theanterior partial thickness cavity further comprises forming the basesurface to have a shape selected from the group consisting of a convexand concave.
 15. A method of making a lens for refractive tear shaping,the method comprising: determining a refractive correction for the lens;determining a size and a shape of an anterior partial thickness cavityto be formed in the lens, based on the determined refractive correction;forming a curved lens body from an optically transparent material, thecurved lens body having a peripheral edge; forming the anterior partialthickness cavity in an anterior surface of the lens body, wherein theanterior partial thickness cavity comprises: an anterior facing basesurface; and an edge, wherein the anterior facing base surface and theedge are sized and shaped to form a tear lens within the anteriorpartial thickness cavity to provide the determined refractivecorrection, and wherein forming the anterior partial thickness cavitycomprises forming the base surface to have a curvature greater than thatof a posterior surface of the lens body.
 16. The method of claim 15,wherein forming the anterior partial thickness cavity further comprisesforming the base surface to have a diffractive surface.
 17. The methodof claim 16, wherein the diffractive surface is defined byrn=2nfλ wherein rn represents a radius of curvature of the diffractivesurface, n represents a refractive index or a refractive indexdifference, if the diffractive surface is immersed in a fluid having arefractive index other than air, f represents a focal length and λ is awavelength of light.
 18. The method of claim 16, wherein forming theanterior partial thickness cavity further comprises forming the basesurface to have a shape selected from the group consisting of a convexand concave.
 19. The method of claim 15, wherein forming the anteriorpartial thickness cavity further comprises positioning the anteriorpartial thickness cavity at an optical center of the lens body.
 20. Themethod of claim 15, wherein a thickness of the lens body from the basesurface to a posterior surface of the lens body is in a range of 10 μmto 100 μm.